The Kentucky Republican's bill would meet a supplemental funding request from the Pentagon for $225 million for the program. Senate Appropriations Chairwoman Barbara A. Mikulski, D-Md., included the funding in her much broader supplemental that would primarily address the crisis of unaccompanied migrant children entering the United States from Central America — but Republicans are balking at that $3.6 billion bill.

"Republicans are united in support of our ally Israel. We have legislation that would allow Congress to meet the Secretary's request. And we hope our friends on the other side will join us in coming to a sensible, bipartisan solution that can be passed quickly," McConnell said in a floor speech. "As most senators know, the Iron Dome missile defense system has played a critical role in defending Israel's population from the rocket attacks launched by Hamas from within the Gaza Strip.

"By passing a bipartisan measure to meet the secretary's request, we can send a message to Hamas that its terrorist tactics and its attempts to terrorize Israel's populace will not succeed," he said.

Republicans aren't happy that Mikulski's bill would not make changes to a 2008 anti-trafficking law. The two parties remain far apart on the best way to address the immigration crisis. McConnell's move allows Republicans to demonstrate that they are supportive of the requested funds for defense of Israel even if they oppose the broader package.

But it likely does not speak well to the prospects that the two sides will reach a deal.